Optically referenced 300 GHz millimetre-wave oscillator

Optical frequency division via optical frequency combs has enabled a leap in microwave metrology, leading to noise performance never explored before. Extending this method to the millimetre-wave and terahertz-wave domains is of great interest. Dissipative Kerr solitons in integrated photonic chips offer the unique feature of delivering optical frequency combs with ultrahigh repetition rates from 10 GHz to 1 THz, making them relevant gears for performing optical frequency division in the millimetre-wave and terahertz-wave domains. We experimentally demonstrate the optical frequency division of an optically carried 3.6 THz reference down to 300 GHz through a dissipative Kerr soliton, photodetected with an ultrafast uni-travelling-carrier photodiode. A new measurement system, based on the characterization of a microwave reference phase locked to the 300 GHz signal under test, yields attosecond-level timing-noise sensitivity, overcoming conventional technical limitations. This work places dissipative Kerr solitons as a leading technology in the millimetre-wave and terahertz-wave field, promising breakthroughs in fundamental and civilian applications. A 300 GHz signal is generated by the combination of a low-noise stimulated Brillouin scattering process, dissipative Kerr soliton comb and optical-to-electrical conversion. A phase noise of −100 dBc Hz−1 is achieved at a Fourier frequency of 10 kHz.